Hi, I have been working on some muddy scenes using very short sound clips that were taken from various sources on YouTube. The muddy scenes have no actual video footage only the sound clips of the action and a text monologue that I typed on screen to describe what the mudder is doing. If I posted such media here or on YouTube would I get into trouble?

Put simply, if someone else has created the audio you cannot use it - even just short clips - without the copyright holder's permission.

YouTube has a ContentID tool that automatically checks videos for copyright infringement.

That doesn't mean material infringing copyright doesn't get uploaded of course. Depending on what YouTube has agreed with the rights holders, some videos can stay online but the uploader cannot monetise them.

I should also add that having had written work I've done in another sector plagiarised by another writer it was so immediately obvious when I first saw it.

Copyright is a complex issue and there are exceptions for what is known as "fair dealing" but to stay on the safe side, you should only upload videos that are entirely your own work.